The proposed study will compare the etiology of drug use and drug escalation for black and hispanic adolescents with the etiology of drug use among white youth. It will focus on the structure, function and composition of adolescent social networks and the changes that occur in those social networks to determine their effect on drug use. Neighborhood and cultural differences are seen as important influences on the type of social networks that are formed and maintained especially in areas of different racial and ethnic composition, and as interacting with social network characteristics in their effect on patterns of drug use. The relationship between social network characteristics and drug use is seen as reciprocal. That is, the characteristics of adolescent social networks are seen as affecting the patterns of drug use and drug use is, in turn, seen as having an effect on the characteristics of a social network. In cooperation with a project already funded by the Office of Juvenile Justice and Delinquency Prevention, the sample will be drawn from a population of adolescents in the Rochester City school system. By oversampling high delinquency low SES areas, we expect to acquire a sample that not only disproportionately represents minority groups, but also one that over represents problem drug users. Interviews will be conducted with adolescents and their parents or care-taking guardian at six month intervals. Additional information will be acquired from teacher questionnaries, school records, criminal justice records and community characteristics of the 64 residential neighborhoods of Rochester. Funding for three waves of data collection is being requested, now, but the overall project is designed as a four year, seven wave panel study. The longitudinal design will allow for an examination of causal relationships, reciprocal effects and instability in network composition.